Re: BGP question [7:40525]
I have seen it happen in lab environments. For the most part, it isn't pretty. It's the worst with OSPF as it isn't possible to get to 100k+ prefixes in ISIS (cap is 32k I believe due to LSP sizes & max fragments) In my lab, I had to reboot all my cisco devices (4700's, 7513's, 2600's & access servers) Some simply locked or rebooted themselves, others became inoperable. Further, one needs to purge the LSA's from the LSDB, otherwise, they will continue to try and flood which makes the problem hard to fix when your originating router doesn't accept commands from the cli :) At 10:50 PM 4/5/2002 -0500, MADMAN wrote: >You hit the nail on the head and this is why I think synchronization is a >legacy >default attribute. If you redistributed the Internet routing table into an >IGP I think >you would not like the results. I have not tried this, has anyone > > Dave > >"[EMAIL PROTECTED]" wrote: > > > I'm no BGP guru, but I would have thought also that redistributing *full > > routes* (as opposed to a default) into your IGP might overload internal > > routers rather badly. The original poster referred to 2600s and 3600s > > inside the AS. > > > > JMcL > > - Forwarded by Jenny Mcleod/NSO/CSDA on 05/04/2002 09:36 am - > > > > "Lomker, Michael" > > Sent by: [EMAIL PROTECTED] > > 05/04/2002 08:38 am > > Please respond to "Lomker, Michael" > > > > > > To: [EMAIL PROTECTED] > > cc: > > Subject:RE: BGP question [7:40525] > > > > > Why is redistribution into an IGP a big no - no? My > > > understanding is that this is what people usually do. > > > > You'd have to be careful about advertising those routes back out to BGP > > again. There was a famous case of someone bringing down the Internet by > > creating such a loop. Needless to say, their ISP shouldn't have been > > accepting advertisements for networks that the company didn't own. >-- >David Madland >CCIE# 2016 >Sr. Network Engineer >Qwest Communications Inc. >612-664-3367 >[EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=40680&t=40525 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: BGP question [7:40525]
Simple. Run HSRP between the two routers. All packets are sent to the active router and if the other 7206 has a better route the packet goes back on to the LAN and out that 7206's Internet link. Dave "Steven A. Ridder" wrote: > If I had 2 7206 routers dual homed to two different ISP's for redundancy, I > know I don't NEED the full bgp table, but if I were to accept them for > optimal routing within my network, how would I tell my internal routers who > don;t run BGP which of the two 7206 routers to go to for a specific route > oout to the internet? I assume doing a redistribution into the IGP is a big > no-no, so how do small 3600's and 2600's inside the AS know which of the two > routers to send the traffic to based on the fact that that one router has > the better route? > > I can think of adding a third 7206 router which would run BGP, connect to > the other two routers and accept the full table as well, and the internal > routers would use that one as the gateway to the internet, but if I didn't > have that third router, is there any other way? > > -- > > RFC 1149 Compliant. > Get in my head: > http://sar.dynu.com -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications Inc. 612-664-3367 [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=40666&t=40525 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: BGP question [7:40525]
There is absolutely no problem accepting full routes from two ISPs providing you have 128M memory in a sufficient router with synchronization disabled, (see earlier post). I have done this several times. Dave Alex Lei wrote: > That pretty much rules out redistributing into IGP. I am thinking that > Steve's original suggestion is the only way to go, but I feel that there may > be a problem accepting full routes from two different providers. > > Any comments? > > Alex > > [EMAIL PROTECTED] wrote: > > > > I'm no BGP guru, but I would have thought also that > > redistributing *full > > routes* (as opposed to a default) into your IGP might overload > > internal > > routers rather badly. The original poster referred to 2600s > > and 3600s > > inside the AS. > > > > JMcL > > - Forwarded by Jenny Mcleod/NSO/CSDA on 05/04/2002 09:36 am > > - > > > > > > "Lomker, Michael" > > Sent by: [EMAIL PROTECTED] > > 05/04/2002 08:38 am > > Please respond to "Lomker, Michael" > > > > > > To: [EMAIL PROTECTED] > > cc: > > Subject:RE: BGP question [7:40525] > > > > > > > Why is redistribution into an IGP a big no - no? My > > > understanding is that this is what people usually do. > > > > You'd have to be careful about advertising those routes back > > out to BGP > > again. There was a famous case of someone bringing down the > > Internet by > > creating such a loop. Needless to say, their ISP shouldn't > > have been > > accepting advertisements for networks that the company didn't > > own. -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications Inc. 612-664-3367 [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=40665&t=40525 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: BGP question [7:40525]
You hit the nail on the head and this is why I think synchronization is a legacy default attribute. If you redistributed the Internet routing table into an IGP I think you would not like the results. I have not tried this, has anyone Dave "[EMAIL PROTECTED]" wrote: > I'm no BGP guru, but I would have thought also that redistributing *full > routes* (as opposed to a default) into your IGP might overload internal > routers rather badly. The original poster referred to 2600s and 3600s > inside the AS. > > JMcL > - Forwarded by Jenny Mcleod/NSO/CSDA on 05/04/2002 09:36 am - > > "Lomker, Michael" > Sent by: [EMAIL PROTECTED] > 05/04/2002 08:38 am > Please respond to "Lomker, Michael" > > > To: [EMAIL PROTECTED] > cc: > Subject:RE: BGP question [7:40525] > > > Why is redistribution into an IGP a big no - no? My > > understanding is that this is what people usually do. > > You'd have to be careful about advertising those routes back out to BGP > again. There was a famous case of someone bringing down the Internet by > creating such a loop. Needless to say, their ISP shouldn't have been > accepting advertisements for networks that the company didn't own. -- David Madland CCIE# 2016 Sr. Network Engineer Qwest Communications Inc. 612-664-3367 [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=40663&t=40525 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: BGP question [7:40525]
This is how I would skin this cat ;) Run Ethernet between your two gateway routers, then make them IBGP peers. Have have your other routers connected to both gateway routers. Your 3600, and 2600's should then do per-dest load balancing for their default route. The smaller routers send their traffic to on of the gateway routers, then allow the gateway routers decide between themself which is the best route out. You may not always get the most optaimal route (one extra hop), but it will work and will save you from have to buy another router, and setting your self up for a Single Point of Failure. We are about to add a second gateway router ourself and this is the way we are going, until we can push IBGP futher into our core. John Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=40636&t=40525 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: BGP question [7:40525]
Steve, If it is optimal routing that your after, I would think that you could still have your some of your internal 3600's or 2600's run BGP with your 2 gateway routers, but just don't send the full internet routing table to them. For instance, you could possibly put up as-path filters to allow only your local ISP's and their respective customer's routes to be passed to your internal routers that sit immediately behind your 2 gateway routers. That way your outbound traffic will have at least some routing information to make a decision. While this setup is not as optimal as having a full internet routing table, I would think this would allow for more optimal routing then just using defaults. I have customers at my work with 3600's with appropriate amount of memory that are multihomed handling 30,000+ routes from each provider comfortably. greg Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=40619&t=40525 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: BGP question [7:40525]
Short answer. If you want all the routers in your AS to have full knowledge of prefixes, buy some memory and extend your BGP cloud to include them. Otherwise, follow a dynamic default and live with suboptimal routing. Adding the third router as you suggest is a helpful option. However, in most cases, outbound traffic load is really not the problem (which is unfortunate as it's actually possible to manipulate with some accuracy) Inbound is the killer. At 04:28 PM 4/4/2002 -0500, Steven A. Ridder wrote: >If I had 2 7206 routers dual homed to two different ISP's for redundancy, I >know I don't NEED the full bgp table, but if I were to accept them for >optimal routing within my network, how would I tell my internal routers who >don;t run BGP which of the two 7206 routers to go to for a specific route >oout to the internet? I assume doing a redistribution into the IGP is a big >no-no, so how do small 3600's and 2600's inside the AS know which of the two >routers to send the traffic to based on the fact that that one router has >the better route? > >I can think of adding a third 7206 router which would run BGP, connect to >the other two routers and accept the full table as well, and the internal >routers would use that one as the gateway to the internet, but if I didn't >have that third router, is there any other way? > >-- > >RFC 1149 Compliant. >Get in my head: >http://sar.dynu.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=40599&t=40525 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: BGP question [7:40525]
aren't the 2 7206 dual homed, 2 connections to each ISP? why not run hsrp on the 7206 and let those routers make decisions for all internal routers? >From: "Ouellette, Tim" >Reply-To: "Ouellette, Tim" >To: [EMAIL PROTECTED] >Subject: RE: BGP question [7:40525] >Date: Thu, 4 Apr 2002 18:39:17 -0500 > >This can be simplified in the following way. > >If you want your internal routers to be able to make a routing decision >based on an external bgp route that is somewhere on the net that I'd think >your internal router (3660) has to have that route in it's routing table >(maybe redistributed into some IGP from BGP). Maybe not the best way. > >Or, you could inject default routes from each BGP speaker (your 7200's) >into >your IGP. If let's say one of your 3600's send a packet to it's default >gateway (one of the 7200)'s which in turn could pass it over ethernet to >the >other 7200 if you setup some policy routing etc. > >I'd say you might want have your 2600/3600's connected to both 7200's for >redundancy in case one box completely fails it'll use the other. This >could >be done be accepting the default routes from each 7200 or by creating a >floating static that way if the primary route to the internet fails, it'll >use a backup. These are just a couple of ideas. If you provide some >specifics of the layout, I may be able to help out a bit more. Also, I'm >sure some of the experts here will provide much better detail of how >they've >implemented such a design. > >In short, I'm thinking that if you want a 2600/3600 to make a decision on >which 7200 to go out of for a specific route, it has to know about it. > >Tim > >-Original Message- >From: Steven A. Ridder [mailto:[EMAIL PROTECTED]] >Sent: Thursday, April 04, 2002 4:29 PM >To: [EMAIL PROTECTED] >Subject: BGP question [7:40525] > > >If I had 2 7206 routers dual homed to two different ISP's for redundancy, I >know I don't NEED the full bgp table, but if I were to accept them for >optimal routing within my network, how would I tell my internal routers who >don;t run BGP which of the two 7206 routers to go to for a specific route >oout to the internet? I assume doing a redistribution into the IGP is a >big >no-no, so how do small 3600's and 2600's inside the AS know which of the >two >routers to send the traffic to based on the fact that that one router has >the better route? > >I can think of adding a third 7206 router which would run BGP, connect to >the other two routers and accept the full table as well, and the internal >routers would use that one as the gateway to the internet, but if I didn't >have that third router, is there any other way? > >-- > >RFC 1149 Compliant. >Get in my head: >http://sar.dynu.com _ Chat with friends online, try MSN Messenger: http://messenger.msn.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=40592&t=40525 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: BGP question [7:40525]
It is absolutely not what people do, at least they better not be doing that. Think about this. The current BGP route table is about 100,000 routes. If you want redundancy, that means multiple routers as ASBR's, and if you're talking OSPF as an IGP, then each ASBR then has to generate a type-5 LSA for each of those BGP routes. Therefore that means having hundreds of thousands of type-5 LSA's running around on your network - can you imagine? Just thinking about it makes me shudder. Of course you might say that you might try to summarize those LSA's by using totally stubby areas. Well, first of all that doesn't exactly help your core (area 0 can't be stubby), and second of all if you were going to use default routes anyway (via totally stubby ABR's), then why not forgo redistribution completely and just have your ASBR's inject defaults? ""Alex Lei"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Steve, > > Why is redistribution into an IGP a big no - no? My understanding is that > this is what people usually do. > > If you use OSPF and E2 routes on the third router, then OSPF should find the > optimal route. > > Alex > > Steven A. Ridder wrote: > > > > If I had 2 7206 routers dual homed to two different ISP's for > > redundancy, I > > know I don't NEED the full bgp table, but if I were to accept > > them for > > optimal routing within my network, how would I tell my internal > > routers who > > don;t run BGP which of the two 7206 routers to go to for a > > specific route > > oout to the internet? I assume doing a redistribution into the > > IGP is a big > > no-no, so how do small 3600's and 2600's inside the AS know > > which of the two > > routers to send the traffic to based on the fact that that one > > router has > > the better route? > > > > I can think of adding a third 7206 router which would run BGP, > > connect to > > the other two routers and accept the full table as well, and > > the internal > > routers would use that one as the gateway to the internet, but > > if I didn't > > have that third router, is there any other way? > > > > -- > > > > RFC 1149 Compliant. > > Get in my head: > > http://sar.dynu.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=40566&t=40525 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: BGP question [7:40525]
That pretty much rules out redistributing into IGP. I am thinking that Steve's original suggestion is the only way to go, but I feel that there may be a problem accepting full routes from two different providers. Any comments? Alex [EMAIL PROTECTED] wrote: > > I'm no BGP guru, but I would have thought also that > redistributing *full > routes* (as opposed to a default) into your IGP might overload > internal > routers rather badly. The original poster referred to 2600s > and 3600s > inside the AS. > > JMcL > - Forwarded by Jenny Mcleod/NSO/CSDA on 05/04/2002 09:36 am > - > > > "Lomker, Michael" > Sent by: [EMAIL PROTECTED] > 05/04/2002 08:38 am > Please respond to "Lomker, Michael" > > > To: [EMAIL PROTECTED] > cc: > Subject:RE: BGP question [7:40525] > > > > Why is redistribution into an IGP a big no - no? My > > understanding is that this is what people usually do. > > You'd have to be careful about advertising those routes back > out to BGP > again. There was a famous case of someone bringing down the > Internet by > creating such a loop. Needless to say, their ISP shouldn't > have been > accepting advertisements for networks that the company didn't > own. > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=40548&t=40525 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: BGP question [7:40525]
I'm no BGP guru, but I would have thought also that redistributing *full
routes* (as opposed to a default) into your IGP might overload internal
routers rather badly. The original poster referred to 2600s and 3600s
inside the AS.
JMcL
- Forwarded by Jenny Mcleod/NSO/CSDA on 05/04/2002 09:36 am -
"Lomker, Michael"
Sent by: [EMAIL PROTECTED]
05/04/2002 08:38 am
Please respond to "Lomker, Michael"
To: [EMAIL PROTECTED]
cc:
Subject: RE: BGP question [7:40525]
> Why is redistribution into an IGP a big no - no? My
> understanding is that this is what people usually do.
You'd have to be careful about advertising those routes back out to BGP
again. There was a famous case of someone bringing down the Internet by
creating such a loop. Needless to say, their ISP shouldn't have been
accepting advertisements for networks that the company didn't own.
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=40546&t=40525
--
FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: BGP question [7:40525]
This can be simplified in the following way. If you want your internal routers to be able to make a routing decision based on an external bgp route that is somewhere on the net that I'd think your internal router (3660) has to have that route in it's routing table (maybe redistributed into some IGP from BGP). Maybe not the best way. Or, you could inject default routes from each BGP speaker (your 7200's) into your IGP. If let's say one of your 3600's send a packet to it's default gateway (one of the 7200)'s which in turn could pass it over ethernet to the other 7200 if you setup some policy routing etc. I'd say you might want have your 2600/3600's connected to both 7200's for redundancy in case one box completely fails it'll use the other. This could be done be accepting the default routes from each 7200 or by creating a floating static that way if the primary route to the internet fails, it'll use a backup. These are just a couple of ideas. If you provide some specifics of the layout, I may be able to help out a bit more. Also, I'm sure some of the experts here will provide much better detail of how they've implemented such a design. In short, I'm thinking that if you want a 2600/3600 to make a decision on which 7200 to go out of for a specific route, it has to know about it. Tim -Original Message- From: Steven A. Ridder [mailto:[EMAIL PROTECTED]] Sent: Thursday, April 04, 2002 4:29 PM To: [EMAIL PROTECTED] Subject: BGP question [7:40525] If I had 2 7206 routers dual homed to two different ISP's for redundancy, I know I don't NEED the full bgp table, but if I were to accept them for optimal routing within my network, how would I tell my internal routers who don;t run BGP which of the two 7206 routers to go to for a specific route oout to the internet? I assume doing a redistribution into the IGP is a big no-no, so how do small 3600's and 2600's inside the AS know which of the two routers to send the traffic to based on the fact that that one router has the better route? I can think of adding a third 7206 router which would run BGP, connect to the other two routers and accept the full table as well, and the internal routers would use that one as the gateway to the internet, but if I didn't have that third router, is there any other way? -- RFC 1149 Compliant. Get in my head: http://sar.dynu.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=40545&t=40525 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: BGP question [7:40525]
Smaller routers couldn't handle all these routes. Can anybody say "mushroom cloud"? ""Lomker, Michael"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > Why is redistribution into an IGP a big no - no? My > > understanding is that this is what people usually do. > > You'd have to be careful about advertising those routes back out to BGP > again. There was a famous case of someone bringing down the Internet by > creating such a loop. Needless to say, their ISP shouldn't have been > accepting advertisements for networks that the company didn't own. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=40543&t=40525 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: BGP question [7:40525]
> Why is redistribution into an IGP a big no - no? My > understanding is that this is what people usually do. You'd have to be careful about advertising those routes back out to BGP again. There was a famous case of someone bringing down the Internet by creating such a loop. Needless to say, their ISP shouldn't have been accepting advertisements for networks that the company didn't own. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=40537&t=40525 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: BGP question [7:40525]
Steve, Why is redistribution into an IGP a big no - no? My understanding is that this is what people usually do. If you use OSPF and E2 routes on the third router, then OSPF should find the optimal route. Alex Steven A. Ridder wrote: > > If I had 2 7206 routers dual homed to two different ISP's for > redundancy, I > know I don't NEED the full bgp table, but if I were to accept > them for > optimal routing within my network, how would I tell my internal > routers who > don;t run BGP which of the two 7206 routers to go to for a > specific route > oout to the internet? I assume doing a redistribution into the > IGP is a big > no-no, so how do small 3600's and 2600's inside the AS know > which of the two > routers to send the traffic to based on the fact that that one > router has > the better route? > > I can think of adding a third 7206 router which would run BGP, > connect to > the other two routers and accept the full table as well, and > the internal > routers would use that one as the gateway to the internet, but > if I didn't > have that third router, is there any other way? > > -- > > RFC 1149 Compliant. > Get in my head: > http://sar.dynu.com > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=40532&t=40525 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
